In power distribution network, especially in a rural power distribution network of China, load break switch (LBS) are widely applied in secondary ring main units, wherein about 50% of the load break switches are sulfur hexafluoride (SF6) load break switch with advantages of reliable insulation and small device size. However, the sulfur hexafluoride load break switches are not environmentally friendly. The other 25% of load break switch are vacuum load break switch with the advantages of reliable insulation and being environmentally friendly but having a large device size.
In the prior art, owing to the powerful making and breaking capability and insulating performance of SF6, SF6 load break switch with sulfur hexafluoride as insulating medium can be very compact in terms of product size and can well meet the spatial requirement of secondary ring main units. However, with people's growing awareness of importance of environment protection, sulfur hexafluoride load switch has been gradually phased out because of the defect that its insulating medium is not environmentally friendly. Approximately 1% of sulfur hexafluoride load break switch are replaced by vacuum load break switch each year. However, although the vacuum load break switches in the prior art take vacuum as breaking medium, the majority of the live parts are still completely exposed in the air. In order to achieve the purpose of reliable insulation, the product size must be large enough, resulting in a waste of space to a large extent.
In order to make best use of the advantages and avoid the disadvantages, there is provided a new solution for vacuum load switch.